Electric tool.



ELECTRIC TOOL.

APPLICATION FILED JULY 20, 1908.

996,833, Patented July 4, 1911.

2 SHEETS-SHEET 1.

C: B. CUATES.

ELEOTRIG TOOL. v AYPLIGATION FILED JULY 20, 1903. 996,833. Patented July4, 1911.

2 SHEETS-SHEET 2.

unrrnlo CHARLES E. COAIES, 01 OEICAGO, ELLINQIS, .ASSIG-NGB if} GA'GOPNETJ'ZR'KATIG T 301;

COMPANY, 015 CHICAGO, ILLLNGIS,

A fJElRPfiEATIULtT NEW anaemic root.

To all whom it may concern:

Be it known that l, CHARLES E. Gowns, a citizen of the United States,residing at Chicago, Cook county, Illinois, have in vented certain newand useful Improvements in Electric Tools, of which the following is aspecification.

My invention relates to tools of the port able type actuated byelectricity and. intended for variouskinds of work wherever a rotaryworking tool is to be operated and heobject of such invention, broadlyspeale ing, is to provide novel and efiicient means for controlling thecurrent of electricity for such tools.

Heretofore electric tools of this character 5 have been provided withswitch ineciianisin designed for the normal an'munt of current, but inpractice when the actuating' or other working tool becomes stuck in thework or is heavily over-loaded, due to heavy feeding, the operatorinvariably opens the switch, with resultant heavy and destructive arcingat the contacts. To overcome this diliiculty in a simple manner andwithout increasing the weight ol 'the tool is one of the main objects ofmy invention, and to this end I arrange in or on the tool a pilot switchunder the control of the'operator and within convenient reach of one ofhis hands which grasps the tool and adapted to control a main switchlocated elsewhere than on the tool and of such size or massive characterthat would prochide its employment in the electric tool which, beingportable, as stated, must be made as light as possible.-

jrnother object of my invention is to provide-means for automaticallyopening the circuit at a predetermined load on the tool, therebyproviding for a definite point of release or stopping of the electrictool-when several exactly similar operations are to he. performed, suchas the driving of lag screws, rolling of boiler lines, etc, resulting iabsolute uniformity in the worlc. Thus, at the con'ipletion oi the workthe tool is automatically stopped. At the same time the operator'isenabled to stop the, tool at will and at any stage of the work byoperating the socalled pilot switch and may start-the tool again byoperating another button or actuating member of such switch,

My invention is particularly useful in railroad or street railwayconstruction in connection with the d 'iving-of lag screws,

Specification of Letters rateareaaei 4, ion.

' elects.

which are now taking the place of the nsual spikes for holding the railsto the ties, and while, for the purpose of a clear description of myinvention, l have chosen to describe the same in that particularconnection, yet it will he understood that my electric tool so providedwith this system of switches is capable of a variity of uses and lcontenr' plate u ing my invention wherever applicable and in differentenvironments.

listening to the accompanying drawings, Figure l is a perspectiveshowing the elec tric tool in pie for the driving of lag screws instreet lway construct-ion work, the, main switch being locatedelsewhere-or separate from the tool andhcre shown snepend-ed from thensualtrolley .wire from which Lhe current is obtained; Fig. 2 anelevation ol the electric drill with a portion thereof-broken away andillustrating the Jllpt switch in section; Fig. 3 a side elevation of hepilot switch alone; Fi 1- a section taken on the line lof Fig. 3; Fig.an elevation of the main switch; and Fig. (5 a diagram illustrating theelectrical circuits, etc. v

Referring to the present emoodimentof my invention and to the particularuse thereof as illustrated in the drawings, the electric motor isprovided with a casing 1 having at opposite sides the usual graspinghandles 2 and containing an electric motor indicated at 3, which motoris operatively connected in suitable manner to the chuck 4 into whichthe cutting or other working tool is inserted. A comparatively small andlight switch, which I will hereinafter term the pilot switch, isassociated with the electric drill and forms one of the component partsthereof, This pilot switch is adapted. to he located in or on theelectric drill, but'in the present instance it is shown as locatedwithin the casing with its buttons or operating members projecting up'ardly through the top wall of an extension plate 5 having a boss intowhich one of the handles 9 is screwed or otherwise secured, as clearlyindicatcd in Fig. 2. This pilot switch does not directly control thecurrent to the elec-- lric tool, hut acts upon or controls-the mainswitch, which is ai-itomatically controlled as to sloppinn' by theamount of current admitted to or passing through the motor. In order toproperly take Till (3 ot' the current, the main switch is made ofconsiderable size the tool but in the same electrical circuitstherewith. In the particular.character of 1 use shown in the drawings,said switch is for convenience suspended from the usual trolley wire. I

The pilot switch may be of any suitable construction whereby either oneof two contacts may be connected with a third contact at the will of theoperator and, inasmuch as the particularswitch herein shown is suit ableand efficient for this purpose, I will now describe the samewithoutintending to limit myself to its particular construction. Thisswitch is provided with a frame-(S secured in suitable manner within theextension casing 5, hereinbefore described, and having at its upper endopenings through which pass plungers or push buttons 7 and 8, one forstarting the motor and the other for stopping it. These push buttonspass through the extension casing -and are in such positon relative toone of the grasping handles that the operator is enabled to convenientlydepress one or the other of the push buttons without releasing his graspupon the grasping handlef These push. buttons are upwardlyspring-pressed by means of coiled springs 9 encircling the lower endthereof and pressing downwardly against the frame and upwardly againstthe blocks 10 secured to or forming a part of said push buttons. Totheir inner faces these blocks are provided with spring plates 11, towhose lower ends aresecurcd the shoes 1:2 and 13.

Upon an insulating block 14 secured to the frame 6 is secured atransverse contact 15 which is common to both of said shoes and normallyin contact with both of them. This insulating block is also providedwith the separate contacts 1.6; and 17 which are connected with thecircuits hereinafter described in connection with the diagram. It willbe understood that contact is made between the common contact and one orthe other of the separate contacts. according to whichever one of thesepush buttons is depressed and it will also be understood that inpractice it is intended that one or the other push buttons should bemomentarily depressed by the operator and then released and not be helddown for any period of time. The common contact and the two separatecontacts are provided with suitable binding posts 18;

Referring next to the main switch, which- 1s controlled by the pilotswitch. the same is a magnetically operated switch indicated in generalby the reference Cl121ItlCi6l.l9 and according to the particular use nowbeing described the same is inclosed in a box or housing 20 andsuspended from a rod or supporting pole 21 having a conducting wire -21whose upper end is crooked forsuspension from the trolley wire 22. Theconneceeaes tions between this main switch and the pilot switch arecarried through a cable 23, indicated in Fig. 1 and another'cable 23 ispro vided to run to ground. In practice, in the particular character ofwork specified, the ground wires are connected with the rails.

This main switch is provided with a series of contacts, electromagnets,and with a movable arm which will be understood from the followingdescription of the electrical circuits: In the diagram, Fig. 6, theessential parts of the motor are represented, the armature at 24, thebrushes at 25 and the fields at 26. As shown, the motor isseries-connected but it is obvious that either shunt or compoundwindings may be used. The main switch consists essentially of a coil 27which, when energized by the passage of the our rent, causes a lever arm28 fulcrumed upon the plate 29 to make contact at 30 and 31, placingthese three points 29, 30 and 31 at the same potential. This main switchis also provided with two resistance coils and 38 and also a magnet coil34 adapted'to energize a core of magnetic material and attract the levcr35 making contact at 36. In the diagram the pilot switch is forconvenience shown as having the shoes 12 and '13 secured to the sides ofthe push buttons 7 and 8 respectively and are adapted to be depressed toplace the main or common contact 15 in contact with either one of thetwo separate contacts 16 and 17. The line wires and the connecting wiresbetween the various instrumentalities described will be explained. inconnection with'the operation of the tool. I

When the push button 8, which in the presentinstance may be termed thestarting button, is operated, contact is made between points or contacts15 and 17 and a circuit is thereupon established through the line 37 tothe binding post38, through wire 39, through the resistance coil post orconnection 4-0, magnet coil 27, post or connection 41, wire i2, postorconnection 43', post 44-, wire 45, contacts 15, 13 and 1.7, thencethrough wire 46, binding post 47, wire 48 to post or connection 49. wireto binding post .51 and thence to the return line 52. It will be seenthat a current will flow through the magnet coil 27 with the result thatthe switch arm 28 will be drawn up or attracted so as to make contact at80 and 31. This now establishes another circuit as follows: from theline 37 through post 38, .resistance coil 38. post or connection 40,magnet coil 27, post or connection 4-1, resistance coil 32, contact 30,through the switch arm 28 to contact 31,

wire 53 to point- 54, magnet coil 34, point 36. post or connection 49through the wire 55,

wire 50 and post 51 to the return line Consequently, the coil 27 is nowenergized through a circuit independent of the push button 8, which cannow be released and the circuit still be maintained. The main circuitthrough the motor is now as follows: from the line 37 to post 38, wire56 to binding post 57, wire 58 to the brushes and armature 24, wire 59to one ofthe fieldsQG through the wire 60 to the other field 26, wire 61to the binding post 62, wire 63 to plate 29, through the switcharm 28 tothe contact-31, through wire 53, point 5d, magnet coil 34, connection49, wire 50 and binding'post 51 to the return line 52 to .the other sideof the'line. Thus the motor will start up and operate on the linecurrent. It is to be observed that the coil 27, with the resistancecoils 32 and 33, arein series with each other but in shunt across theline, while the coil 34 carries the main current and will fluctuate withthe load on the motor.

Assuming that the motor circuit is thus established, and the motor isrunning and it isnow desired to stop the motor, this is done bydepressing theother push button 7, with 'the result that a circuit isestablished as follows: from the line 37, post 38, wire 39, re'-sistance 33, post 40,Wl1 64L, binding post 65, Wire 66, contacts 16, 12and 15, wire 45, binding postit, through wire 43 to post 43, wire 42,post or connection 41, resistance 32, contact 30, through the switch armto contact 31, wire 53, point or post 5i, magnet coil 34, point 36, wire55, post or connection 49, wire 50 and binding post 51 to the returnline 52. Thus the path for the current has been made around the magnet27, there- 'by causing the latter to lose its magnetism, and the switcharm to fall by gravity,whereupon the opening of the circuit at 31 causesthe motor to stop. The main switch is adapted to automatically stop themotor at the completion of the work or when any pre determined load isreached, and to this end an adjusting device 67 on the main switchcontrols the position of the lever which is fulcrumed at '68 and itselfcontrols the amount of the air gap between the free end of such leverand the magnet core of the coil.

34. This adjustable device having beensct for a predetermined amount,when the current through the motor reaches that amount this coil 34produces the requisite amount of magnetic energy to attract the lever soas to make contact at the point A circuit is then established asfollows: from the line 37 and binding post 38, wire 39, resistance33,'post or connection 40, wire- (if). wire 70 to point (18, lever 35,contact or point 36, post 49. wire 50 and binding post 51 to thereturnline Thus a circuit has been established around the shunt magnet 27.thereby taking nearlyall of the current out of this magnet and causingits core to lose its magnetism and thereby releasing the switch arm '23,which then falls by gravity. opening the main circuit at the point 31and causing the motor to stop. It l be understood that the switch can beso arranged and the motor stopped at an over-load or a pre- 'determinedload. By the use of my invention I am enabled to provide an electrictool which is portable in character but yet pro- Vided with cooperatingswitch mechanism capable of taking care of all conditions of currentencountered-1n actual practice. T he swltch mechanism 1s under thecontrol. of the operator and the same is moreover auto-' matic andindependent of the operator when it comes tot'he matter of thecompletion of the work, it being understood that the switch mechanismmay be so set as to automatically stop the motor upon the completion ofthe work. Thisis a particularly desirable feature where a series ofsimilar operations. such as driving of lag screws for railroad or streetconstruction work, are to be performed by the electric tool, therebysecuring absolute uniformity of work without any 7 particular skill orattention on the part of the operator.

It will be understood that the particular location of the main switch isnot material so long as it is in the immediate neighborhood of theportable tool which in practice is carried from point to point withinthe range of itscables, and so long as such switch is interposed in theelectrical circuits. The illustrated practical use of my invention shownin Fig. 1 of the drawings pertains to street railway construction whereelectric current is readily available from the trolley wire, but inrailroad construction work or in railroad repair work a section gang maybe provided with an outfit comprising an electric tool, switches andconnections, and suitable means for generating electricity. In an outfitof this character a special hand car may be provided driven by a gasengine, which may be adapted to also drive an electric generator forgenerating the current for operating the electric drill. With suchoutfits lag screws, as substitutes for ordinary railroad spikes, may bereadily, economically and properly driven.

After this disclosure of my invention, many other advantageous usesthereof become obvious.

I claim:

1. in combination with a portable electric tool, a pilot switch. and amain switch mounted independently of the tool governed by the pilotswitch and adapted to interrupt the flow of current to the tool upon theaccomplishment of the desired work; substantially as described.

2. In a portable electric tool, in combination w h such tool, a pilotswitch mounted t e01 nd adapted to be arranged in an elei ill'itnlcircuit, and a main switch located elsewhere than the electric tool butalso adapted to be arranged in said circuit, said. main switch beingadapted to interrupt the flow of currentv to the tool upon theaccomplishment of the desired work; substantially as described.

3. In a portable electric tool, in combination with such' tool, a pilotswitch mounted thereon and) a main switch. governed by the pilot switchfor controlling the admission or interruption of electric current to thetool, said main switch being adjustable for causing interruption of thecurrent when a predetermined load is reached; substantially as described.

4-. In a portable electric tool, in combination with such tool, a pilotswitch mounted thereon, a main switch for controlling the admission orinterruption of electric current tothe tool and adapted to interruptsuch current upon the accomplishment of the desired work, and a cableelectrically connecting the pilot switch and the main switch;substantially as described.

5. In a portable electric tool, in combination with such tool, a pilotswitch mounted thereon, a magnetically operated switch located elsewherethan the tool but connected electrically with the pilot switch, saidlast named switch being adapted to interrupt the current to the toolupon the accomplishment of the desired work; substantially as described.

. 6. In a portable electric tool, in combination with such tool, a pilotswitch mounted thereon, and having separate starting and stoppingpush-buttons arranged to be de- Copies of this patent may be obtained.for

five centseach, by addressing the Commissioner Washington, D. G.

pressed, and a. main switch governed by the pilot switch and adapted tocontrol. the admission and interruption or". electric current to thetool, and to interrupt such current upon the accomplishment of thedesired Work; substantially as described.

7. In a portable electric tool, in combination with such tool, a pilotswitch mounted thereon, 'a main switch for controlling the electricmotor, a main switch supported in-' dependently of the electric motorand a pilot switch mounted'o'n the motor for controlling the mainswitch.

9. In a device of the class described a port able electric toolincluding a motor, a portable main switch provided with means forsuspending it. from an electrical conductor and in electrical contacttherewith, and a pilot switch mounted upon the electric motor andcontrolling the main switch.

CHARLES R. COATES.

Witnesses:

A. L. MURPHY, W. B. SEELIG.

of latents,

